▎WuXi AppTec Content Team Editor
Excessive consumption of sugar is linked to increased rates of non-communicable diseases such as diabetes, cardiovascular disease and cancer. The increased incidence of these diseases is becoming a serious public health problem, killing 35 million people each year. Currently, most trials focus on Western dietary patterns (Western dietary patterns are characterized by higher intakes of red and processed meat, saturated fat, high-fat dairy, eggs, refined grains, sweet potatoes, and high-sugar beverages) Adverse effects on overall health and gut. However, there is not enough research evidence on the specific effects of sugar on health.
The sources of sugar in food are mainly carbohydrates. Recently, a review published in Clinical Gastroenterology and Hepatology aimed to elucidate the role of different types of dietary carbohydrates and their excess intake on intestinal homeostasis and Effects of gastrointestinal disease.
Screenshot source: Clinical Gastroenterology and Hepatology
Carbohydrate metabolism
Carbohydrates are the most important source of dietary energy among macronutrients (40% to 80% of total energy intake).
Carbohydrates have a wide range of physiological roles that are important to health, such as: providing energy, affecting satiety, controlling blood sugar levels (insulin metabolism), affecting protein glycation, Lipid metabolism, bile acid dihydroxylation, fermentation (production of short-chain fatty acids [SCFA], etc.), bowel habits, and gut microbiota.
Considering differences in structure and properties, dietary carbohydrates can be divided into non-digestible carbohydrates (such as fiber) and digestible carbohydrates (sucrose, lactose, and some starches). Among them, digestible carbohydrates need to be degraded into monosaccharides (glucose, fructose, and galactose) before they can be absorbed by the small intestine.
Carbohydrate absorption
The body metabolizes fructose, galactose, and glucose to produce energy. Glucose is a general energy transport molecule in the human body, and the absorption of glucose is mediated by the sodium-glucose co-transporter SGLT1.
Intestinal absorption of fructose appears to be relatively limited compared to glucose and is affected by many factors, especially aging. People with poor fructose absorption are prone to diarrhea and flatulence.
Monosaccharides not only regulate the nascent adipogenesis pathway, but also serve as substrates for triglyceride synthesis and export in the form of lipoproteins.
Sugar absorption
Glucose is one of the most tightly controlled physiological variables in the body’s homeostasis, and the liver plays a key role in maintaining homeostasis. Glucose is delivered in a controlled manner through the liver and absorbed by surrounding tissues as needed. Fructose and galactose must be converted into glucose by the liver before they can be used by the body.
Not Absorbed Carbohydrates
About 40 g per day of dietary carbohydrates such as resistant starch, non-starch polysaccharides and oligosaccharides avoid digestion by host enzymes and reach the colon.
When insoluble fiber is poorly or unmetabolized through the gut, resident microorganisms in the distal small intestine and colon rapidly ferment soluble fiber and produce short-chain fatty acids such as acetate, propionate, and Butyric acid.
Butyric acid is one of the most important metabolites produced by microbial fermentation in the gastrointestinal tract. It is the main energy source for colon cells and directly affects the growth and differentiation of colon cells. In addition, butyric acid has a variety of physiological effects, including enhancing the immune barrier of intestinal mucosa.
Image source: 123RF
Excessive sugar intake is associated with multiple gastrointestinal disorders
There is evidence that processed monosaccharides reduce leukocyte phagocytosis and may increase blood levels of inflammatory cytokine markers. In contrast, fiber intake was shown to protect against inflammation. Sugar accumulation in the colon increases osmotic load as well as the fermentation rate of colonic flora, and exacerbates abdominal pain and intestinal dysfunction.
High sugar intake is associated with a variety of tissue and organ dysfunction and can contribute to overweight, cardiovascular disease, type 2 diabetes, insulin resistance, and systemic inflammation.
Irritable Bowel Syndrome
Irritable bowel syndrome is a functional bowel disorder associated with a variety of clinical symptoms, and soluble fiber has been shown to improve symptoms of irritable bowel syndrome. A diet of low FODMAPs (which stands for oligosaccharides, disaccharides, monosaccharides and polyols) is a possible treatment for irritable bowel syndrome.
Low FODMAPsDiet consists of the first letters of 6 words that represent several different types of carbohydrates, which are:
Fructose: Natural fructose is found in fruits and vegetables, such as honey, apples, etc.; it is also found in most processed foods, such as glucose syrup.
Lactose: Natural lactose is present in milk, so dairy products such as yogurt and cheese contain high levels of lactose.
Fructan: Natural fructans are found in foods such as wheat, rye, onions, and garlic.
Galacto-oligosaccharides: Occurs naturally in beans.
Polyols: Common foods with polyols include apples, avocados, blackberries, apricots, cherries, nectarines, cauliflower, mushrooms, etc. They are also common in sugar-free processed foods such as Sorbitol, mannitol, xylitol, polydextrose, and isomalt, etc.
In simple terms, FODMAPs are a class of fermentable sugars and sugar alcohols (carbohydrates) that are not easily digested by the body, including oligosaccharides, lactose, fructose and polyols . Although food itself is not a factor in IBS, some people with digestive problems experience bloating, abdominal pain, and diarrhea (or worsening bowel problems) after eating foods high in FODMAPs. A low-FODMAPs diet, on the other hand, reduces the consumption of foods containing these carbohydrates during the intervention period.
A recent meta-analysis shows that lactose intolerance is more common in people with IBS, but lack of statistical power prevents IBS from being associated with lactose Intolerance correlation. In addition, few studies have elucidated the mechanism by which fermentable carbohydrates may trigger symptoms of IBS.
Inflammatory Bowel Disease
Inflammatory bowel disease (including Crohn’s disease and ulcerative colitis) is a chronic inflammatory disease of the gastrointestinal tract with increasing incidence worldwide, especially among children middle. Different epidemiological data suggest that adoption of a Western dietary pattern is associated with an increased risk of inflammatory bowel disease. In addition, overweight and obesity are well-established risk factors for worsening inflammatory bowel disease. Prospective cohort studies have reported that increased intake of ultra-processed foods is positively associated with an increased risk of inflammatory bowel disease.
In patients with inflammatory bowel disease, dietary exclusion of certain carbohydrates is associated with improved clinical manifestations, disease remission, and mucosal healing.
Colorectal cancer
There is evidence thatsugar intake is positively associated with colorectal cancer. In particular, high fructose intake and obesity have been found to be associated with the prevalence and progression of colorectal cancer. In patients with stage 3 colon cancer, consumption of high sugar-sweetened beverages has been shown to be associated with a significant increase in cancer recurrence and mortality.
Increased total fructose and glucose intakes were associated with increased all-cause mortality in patients with stage 1 to 3 colorectal cancer after diagnosis.
Experimental studies suggest that advanced glycation end products (AGEs) may contribute to colorectal cancer, but prospective epidemiological studies have not been conclusive. Further understanding of the metabolism of AGEs and their dicarbonyl precursors and their role in colorectal cancer development is required.
Conclusion
The way people eat has changed dramatically in recent decades, with excess sugar intake leading to increased incidence of some non-communicable diseases. The World Health Organization recommends freesugars (as defined by the World Health Organization, free sugars are all monosaccharides and diaccharides added to food by the manufacturer, cook or consumer sugar, as well as those naturally occurring in honey, syrups, and fruit juices) intake is reduced to less than 10% of total energy intake, and further reductions to less than 5% are recommended.
Despite growing scientific and medical attention to sugar, specific analysis of the direct effects of sugar on the gut in healthy people is lacking. Therefore, more attention needs to be paid to carbohydrate sources and the overall impact and quality of the diet, rather than individual food components.
Eat plenty of refinedcarbs (especially added sugars and refined grains [like white flour or white bread, etc.]) etc have many negative effects on the gut and immune system. In addition, excessive intake of free sugars leads to an unhealthy diet, weight gain and an increased risk of non-communicable diseases. Therefore, it is important to avoid these unhealthy dietary factors in daily life.